population size

Legacy ID: 
4 179
Publication Title: 

​Potential demographic and genetic effects of a sterilant applied to wild horse mares

Authors: 
Roelle, J.E., S.J. Oyler-McCance
Publication Date: 
2015
Parent Publication Title: 
U.S. Geological Survey
Publication Type: 
Archive number: 
2015/0025 FORT
Species: 
States: 

Pub Abstract: 

Wild horse populations on western ranges can increase rapidly, resulting in the need for the Bureau of Land Management (BLM) to remove animals in order to protect the habitat that horses share with numerous other species. As an alternative to removals, BLM has sought to develop a long-term, perhaps even permanent, contraceptive to aid in reducing population growth rates. With long-term (perhaps even permanent) efficacy of contraception, however, comes increased concern about the genetic health of populations and about the potential for local extirpation. We used simulation modeling to examine the potential demographic and genetic consequences of applying a mare sterilant to wild horse populations. Using the VORTEX software package, we modeled the potential effects of a sterilant on 70 simulated populations having different initial sizes (7 values), growth rates (5 values), and genetic diversity (2 values). For each population, we varied the treatment rate of mares from 0 to 100 percent in increments of 10 percent. For each combination of these treatment levels, we ran 100 stochastic simulations, and we present the results in the form of tables and graphs showing mean population size after 20 years, mean number of removals after 20 years, mean probability of extirpation after 50 years, and mean heterozygosity after 50 years. By choosing one or two combinations of initial population size, population growth rate, and genetic diversity that best represent a herd of interest, a manager can assess the likely effects of a contraceptive program by examining the output tables and graphs representing the selected conditions.

Publication Title: 

Contribution of arctic PRISM to monitoring western hemispheric shorebirds [foreword]

Authors: 
Skagen, S.K., P.A. Smith, B.A. Andres, G. Donaldson, and S. Brown
Publication Date: 
2012
Updated Date (text): 
2013-04-30
Parent Publication Title: 
Arctic shorebirds in North America: A decade of monitoring
Publication Type: 
Archive number: 
2012/0146 FORT

Pub Abstract: 

WHY MONITOR SHOREBIRDS?

Long-term monitoring of populations is of paramount importance to understanding responses of organisms to global environmental change and to evaluating whether conservation practices are yielding intended results through time (Wiens 2009). The population status of many shorebird species, the focus of this volume, remain poorly known. Long-distance migrant shorebirds have proven particularly difficult to monitor, in part because of their highly migratory nature and ranges that extend into highly inaccessible regions. As migrant shorebirds travel the length of the hemisphere, they congregate and disperse in ways that vary among species, locations, and years, presenting serious challenges to designing and implementing monitoring programs...

Publication Title: 

Estimating the population size of island loggerhead shrikes on Santa Rosa and Santa Cruz Islands, USA

Authors: 
Stanley, T., S. Teel, L. Hall, L. Dye, and L. Laughrin
Publication Date: 
2010
Updated Date (text): 
2012-02-06
Parent Publication Title: 
The Wildlife Society 17th Annual Conference
Publication Type: 
Archive number: 
2010/0068 FORT

Pub Abstract: 
Publication Title: 

Final report for “Pilot study to assess the effectiveness of DNA extraction from Gunnison Sage-Grouse feces for use in population estimation studies”

Authors: 
Oyler-McCance, S.J., and J. St John
Publication Date: 
2007
Updated Date (text): 
2008-10-14
Parent Publication Title: 
Publication Type: 
Archive number: 
2007/0127 FORT

Pub Abstract: 
Publication Title: 

Annual survival and population estimates of Mountain Plovers in Southern Phillips County, Montana

Authors: 
Dinsmore, S.J., G.C. White, and F.L. Knopf
Publication Date: 
2003
Updated Date (text): 
2009-05-13
Parent Publication Title: 
Ecological Applications
Publication Type: 
Archive number: 
2003/0034 FORT
States: 

Pub Abstract: 
Publication Title: 

Survey and assessment of amphibian populations in Rocky Mountain National Park

Authors: 
Corn, P.S., M.L. Jennings, and E. Muths
Publication Date: 
1997
Updated Date (text): 
2012-03-26
Parent Publication Title: 
Northwestern Naturalist
Publication Type: 
Archive number: 
1997/0068 MESC
States: 

Pub Abstract: 
Publication Title: 

How many grizzlies in Yellowstone?

Authors: 
Eberhardt, L.L., and R.R. Knight
Publication Date: 
1996
Updated Date (text): 
2009-11-20
Parent Publication Title: 
Journal of Wildlife Management
Publication Type: 
Archive number: 
Species: 

Pub Abstract: 
Publication Title: 

Estimates of shorebird populations in North America

Authors: 
Morrison, R.I.G., R.E. Gill, Jr., B.A. Harrington, S.K. Skagen, G.W. Page, C.L. Gratto-Trevor, and S.M. Haig
Publication Date: 
2001
Updated Date (text): 
2011-01-19
Parent Publication Title: 
Publication Type: 
Archive number: 
2001/0008 MESC-online

Pub Abstract: 

Estimates are presented for the population sizes of 53 species of Nearctic shorebirds occurring regularly in North America, plus four species that breed occasionally. Population estimates range from a few tens to several millions. Overall, population estimates most commonly fall in the range of hundreds of thousands, par-ticularly the low hundreds of thousands; estimated population sizes for large shorebird species currently all fall below 500 000. Population size is inversely related to size (mass) of the species, with a statistically significant negative regression between log(population size) and log(mass). Two outlying groups are evident on the regres-sion graph: one, with populations lower than predicted, includes species considered to be either “at risk” or par-ticularly hard to count, and a second, with populations higher than predicted, includes two species that are hunted. Shorebird population sizes were derived from data obtained by a variety of methods from breeding, migration, and wintering areas, and formal assessments of accuracy of counts or estimates are rarely available. Accurate estimates exist only for a few species that have been the subject of detailed investigation, and the likely accuracy of most estimates is considered poor or low. Population estimates are an integral part of conservation plans being developed for shorebirds in the United States and Canada and may be used to identify areas of key international and regional importance.

Publication Title: 

Population estimates of Nearctic shorebirds

Authors: 
Morrison, R.I.G., R.E. Gill, Jr., B.A. Harrington, S. Skagen, G.W. Page, C.L. Gratto-Trevor, and S.M. Haig
Publication Date: 
2000
Updated Date (text): 
2009-06-05
Parent Publication Title: 
Waterbirds
Publication Type: 
Archive number: 
2000/0059 MESC pdf

Pub Abstract: 
Publication Title: 

Report on the methods to determine population size and trend of grizzly bears at the ecosystem scale

Authors: 
Carney, D., S. Gniadek, R. Harris, W. Kasworm, K.C. Kendall, R. Mace, T. Manley, C. Servheen, A. Sokkalla, W. Wakkinen, J. Waller, and T. Wittinger
Publication Date: 
1996
Updated Date (text): 
2010-12-28
Parent Publication Title: 
Publication Type: 
Archive number: 
1996/0112 MESC

Pub Abstract: 

Pages